The invention relates to an electric circuit breaker, in particular with moulded casing, having a circuit breaker unit for housing the contacts and the operating mechanism of said contacts, and a removable trip unit for housing the thermal and/or magnetic tripping elements associated with the different poles to actuate the mechanism for tripping in case of overload and/or fault. The trip unit for each pole includes a section of power conductor electrically series connected by a disconnectable connection to an associated section of conductor of the circuit breaker unit enclosing the contacts. The tripping elements react to the over-currents and short-circuit of currents flowing through the conductors.
It is known to dispose a range of trip units of different tripping characteristics, with the trip unit being selectively associated with the same circuit breaker unit to constitute circuit breakers of different ratings. When the trip unit is mounted the electrical connection of the power conductors is ensured by tightening connection screws. These screws are inserted between the trip unit and the braid of current supply to the movable contact to permit their access from the front of the circuit breaker, thereby requiring an extension of the conductors and circuit breaker casing. The trip unit fixing is furthermore carried out independently of the electrical connection, thus complicating the user's or distributor's task.
The suppression of the disconnectable connection was already proposed by providing a detection magnetic circuit in two separable parts, one rigidly locked with the trip unit and the other with the circuit breaker unit. This solution is interesting for a thermal trip with current transformer but it is difficult to apply it to a trip device with bimetallic strip carried by a heater.
An object of the present invention is to remedy these disadvantages and to permit the realization of a circuit breaker with a trip unit that is easily removable and has reduced over-all dimensions.
According to the present invention, the disconnectable connection of each conductor includes a connecting lug making an acute angle with the trend of the conductors in the circuit breaker.
The disposition according to an oblique line of the connection lugs permits an oblique disposition of the set-screws and the access holes to the set-screws which are perpendicular to the lugs. These set-screws emerge no longer on the front of the circuit breaker by crossing the whole length of the casing, but rather, on the side face supporting the connecting terminals. The over-all dimensions are thus lengthwise reduced to the detriment of the over-all dimensions in height, but the available room in this zone is sufficient to place the inclined lugs under the mechanism of the trip unit.
At the same time that the set-screws advantageously ensure the fixing of the trip unit on the circuit breaker unit, the connection lugs of one of the units is elastically mounted thereon to compensate for positioning faults and to permit a right contact of the lugs of the three poles of the circuit breaker. The inclined lugs are disposed in the lower part of the trip unit to make the access to these set-screws easier and to ensure a right fixing of the unit. The conductor section associated with the trip unit is turned in loops to cross the magnetic circuit of the electromagnetic release and ends by the inclined connection lug located below this magnetic circuit. This lug is brought into contact with the associated lug supported by the base of the circuit breaker unit when the trip unit release is mounted. The connection zone is thus brought back under the trip unit and the electrodynamic forces generated inside the loop increase the contact pressure of the lugs.